Field of the Invention
The present invention relates to an electrodeless lighting device and a method for manufacturing the same. More specifically, the present invention relates to an electrodeless lighting device and a method for manufacturing the same to reduce a discharge inception voltage and thereby improve initial lighting properties as well as product lifespan and reliability.
Discussion of the Related Art
In general, a lighting device (microwave discharge lamp) using microwaves (microwaves with a wavelength of several hundred MHz to several GHz) is an apparatus that generates visible light by applying microwaves to an electrodeless plasma bulb and has high brightness and high efficiency, when compared to incandescent lamps or fluorescent lamps, and use thereof is gradually increasing.
The microwave lighting device is an electrodeless discharge lamp which includes a quartz bulb filled with inert gas without an electrode and emits visible light of a continuous spectrum while discharging sulfur in a high voltage state and is also referred to as an “electrodeless lighting device”.
The electrodeless lighting device includes a magnetron for generating microwaves, a bulb filled with a light-emitting material so as to emit light when excited by the microwaves, a resonator for accommodating the bulb and for resonating the microwaves, and a waveguide for connecting the magnetron to the resonator.
A light emission principle of the electrodeless lighting device will be described in brief. Microwaves generated by the magnetron are transferred through the waveguide to the resonator. The microwaves entering the resonator are resonated in the resonator and, at the same time, excite a light-emitting material of the bulb. The light-emitting material filling the bulb is thus transformed into plasma, thereby generating light which is emitted to the outside of the resonator.
The bulb of the electrodeless lighting device is filled with a dose, such as sulfur, and inert gas for light emission; however, impurities may be introduced to the bulb in the process of filling the dose and inert gas. Problems including increased discharge inception voltage, decreased luminance efficiency and shortened product lifetime of the electrodeless lighting device are encountered if a large amount of impurities are present in the bulb.